The disclosure relates to a valve, in particular an outlet valve of a hydraulic piston pump for delivering a fluid, comprising a valve seat in which a valve orifice is formed and a valve closing body which is arranged on the valve seat for selectively opening and closing the valve orifice. The disclosure further relates to a hydraulic piston pump and to a vehicle brake system.
Hydraulic piston pumps, as used, for example, in vehicle brake systems, generally have ball valves as inlet and outlet valves, since these are relatively inexpensive to produce.
Such a valve in the form of a ball valve is usually arranged in a valve housing which is clamped to a mounting of a piston capable of reciprocating in a cylinder. The inlet valve is provided so that fluid can be drawn through an inlet device into a pressure region in the interior of the cylinder by means of a stroke movement of the piston. The fluid is then delivered under pressure through the outlet valve from the pressure region into a hydraulic system in order to perform work.
The valve housing is generally configured as a cup-shaped cage in the interior of which a helical return spring which urges against a spherical closing body is located. The spherical closing body thereby bears against a valve seat which is formed on the end face of the piston.
When the piston is pushed out of the cylinder by means of a return spring, therefore, the closing body of the inlet valve is lifted from the valve seat against the force of the return spring, since a negative pressure is built up in the cylinder. During this movement of the piston the inlet valve is opened and fluid is drawn via the inlet device into the pressure region.
When the piston is pushed into the cylinder by means of a cam the inlet valve closes and the outlet valve is opened, in that the closing body thereof is lifted against a spring force of a helical return spring. The fluid is delivered from the pressure region into a hydraulic system in order to perform work.
DE 10 2008 043 841 A1 discloses a ball valve, in particular a high-pressure valve for high-pressure pumps of fuel injection systems, having a valve ball and a valve seat face, the valve ball cooperating with the valve seat face to form a sealing fit for interrupting a connection between an inlet and an outlet. The valve ball is urged against the valve seat face by means of a helical return spring.
Furthermore, DE 10 2004 028 889 A1 discloses a piston pump for delivering hydraulic fluid, comprising a cylinder element, a piston capable of being moved back and forth in the cylinder element and a piston chamber in which the hydraulic fluid can be pressurized by means of the piston. The piston pump further includes an outlet valve and a slot-controlled inlet valve. In the outlet valve, a valve ball is urged against an associated valve seat as a closing body by means of a disk-shaped return spring.